With the rapid development of digital image technology, traditional monochromatic electrophotographic printing is gradually being replaced by full color, high image quality electrophotographic printing. Electrophotographic printing technology enables the making of good quality in-house prints on-demand without requiring professional skills such as those skills used to perform conventional offset printing (lithographic printing) in a printing house.
The print quality of full color electrophotographic printing operations has traditionally been limited by characteristics of the print media. To enhance the image effect in color electrophotographic printing, a coated print media such as paper is often used. Traditional coated print media are coated with pigment compositions and other functional materials configured to promote toner transfer. Additionally, traditional print media coatings and processes are used to enhance the gloss and surface smoothness of the uncoated print media. For the coated print media, a calendaring procedure is often used to apply pressure to the media to achieve high gloss and surface smoothness.
However, the dense pigmented coating used to coat traditional print media creates a situation known as blistering. One of the latter steps of electrophotographic imaging is to permanently fix toner particles on the media surface by applying thermal energy to thermal plastic based toner particles. During this image fusing procedure, moisture in the print media is vaporized due to the local application of high thermal energy by the fusing roller. When the water vapor cannot be discharged from the print media smoothly, it rapidly expands inside the print media and often causes a local delamination of print media layers.
Additionally, the above-mentioned calendaring process increases the density of the coating layer and makes the blistering phenomenon more prominent. Furthermore, advanced electrophotographic printing devices include double headed fuser rollers which apply thermal energy to both sides of the print media during processing at a higher temperature and slower passing speed to increase toner gloss. These processing conditions tend to worsen the anti-blister performance of print media.